Aluminum alloy 6061-T6 (AA 6061-T6) extrusions have been widely applied in large-span reticulated shells. However, researches on behaviors of the aluminum alloy under large deformation and fracture by means of meso-mechanics are still insufficient. This paper focuses on the plastic and fracture behaviors of AA 6061-T6 extrusions over a wide range of stress states. Experiments on smooth and notched round bars, grooved plates and shear plates are conducted. It is observed that the yield stress decreases as the notch or groove radius decreases. The yield stress under plane strain or pure shear is lower than that under axisymmetric tension. In addition, true stress–true strain data obtained from tensile coupon tests overestimate the hardening behavior at large deformation. To fully describe these experimental observations, a new plastic model considering the pressure dependence, Lode angle effect, and hardening with post-necking correction is proposed. Regarding the ductile fracture, modified Mohr–Coulomb fracture model with damage-induced softening is adopted to predict crack initiation and propagation under different stress states. The material models of plasticity and fracture are numerically implemented into FE code ABAQUS/explicit by the material subroutine VUMAT. It is found that both the overall nominal stress–strain curves and fracture patterns for all specimens are well predicted by the material models. For practical engineering design, recommended reduced values of shear strength and high-triaxiality tensile strength of AA 6061-T6 extrusions are given.

铝合金6061-T6（AA 6061-T6）挤压件已广泛应用于大跨度网状壳体。然而，通过细观力学研究铝合金在大变形和断裂下的行为仍然不够。本文重点介绍了AA 6061-T6挤出件在各种应力​​状态下的塑性和断裂行为。进行了光滑且有缺口的圆棒，沟槽板和剪切板的实验。观察到，随着切口或凹槽半径的减小，屈服应力减小。平面应变或纯剪切作用下的屈服应力低于轴对称张力下的屈服应力。此外，从拉伸试样试验获得的真实应力-真实应变数据高估了大变形时的硬化行为。为了全面描述这些实验观察，提出了一种考虑压力依赖性，洛德角效应和颈缩后硬化的新塑性模型。对于延性断裂，采用带有损伤诱导软化的改进的Mohr-Coulomb断裂模型来预测在不同应力状态下的裂纹萌生和扩展。材料子程序VUMAT将可塑性和断裂的材料模型数值化为FE代码ABAQUS / explicit。发现材料模型可以很好地预测所有标本的总体标称应力-应变曲线和断裂模式。对于实际工程设计，给出了建议的降低的AA 6061-T6挤压件的剪切强度和高三轴拉伸强度值。对于延性断裂，采用带有损伤诱导软化的改进的Mohr-Coulomb断裂模型来预测在不同应力状态下的裂纹萌生和扩展。材料子程序VUMAT将可塑性和断裂的材料模型数值化为FE代码ABAQUS / explicit。发现材料模型可以很好地预测所有标本的总体标称应力-应变曲线和断裂模式。对于实际工程设计，给出了建议的降低的AA 6061-T6挤压件的剪切强度和高三轴拉伸强度值。对于延性断裂，采用带有损伤诱导软化的改进的Mohr-Coulomb断裂模型来预测在不同应力状态下的裂纹萌生和扩展。材料子程序VUMAT将可塑性和断裂的材料模型数值化为FE代码ABAQUS / explicit。发现材料模型可以很好地预测所有标本的总体标称应力-应变曲线和断裂模式。对于实际工程设计，给出了建议的降低的AA 6061-T6挤压件的剪切强度和高三轴拉伸强度值。材料子程序VUMAT将可塑性和断裂的材料模型数值化为FE代码ABAQUS / explicit。发现材料模型可以很好地预测所有标本的总体标称应力-应变曲线和断裂模式。对于实际工程设计，给出了建议的降低的AA 6061-T6挤压件的剪切强度和高三轴拉伸强度值。材料子程序VUMAT将可塑性和断裂的材料模型数值化为FE代码ABAQUS / explicit。发现材料模型可以很好地预测所有标本的总体标称应力-应变曲线和断裂模式。对于实际工程设计，给出了建议的降低的AA 6061-T6挤压件的剪切强度和高三轴拉伸强度值。